Among the real numbers a and b, is b a rational number ?
I. a + b is a rational number.
II. a - b is a rational number.

A

If the statement I alone is sufficient to answer the question

B

If the statement II alone is sufficient to answer the question

C

If both the statements I and II are sufficient to answer the question but neither statement alone is sufficient.

D

If both the statements I and II together are not sufficient to answer the question and additional data is required.